The invention relates to a system comprising a magnetic head for detecting information-representing magnetic fields originating from a medium which is movable with respect to the magnetic head, particularly a magnetic recording medium, said magnetic head having a head face with a transducing gap and a magnetically conducting yoke, a magnetoresistive element and an electrically conducting element for generating a magnetic field intersecting the magnetoresistive element, a measuring device connected to the magnetoresistive element and a current device connected to the electrically conducting element.
The invention also relates to a magnetic head having a head face with a transducing gap and a magnetically conducting yoke, a magnetoresistive element and an electrically conducting element for generating a magnetic field intersecting the magnetoresistive element.
Such a system and magnetic head are known from U.S. Pat. No. 3,921,217. The known magnetic head may be a thin-film magnetic head which, starting from a substrate, is built up lengthwise. The known magnetic head comprises two aligned flux-guiding layer parts of a magnetically permeable material between which a gap is present, with a magnetoresistive element bridging the gap. Together with the magnetically conducting substrate, said layer parts form a magnetic yoke for supplying a magnetic flux from a recording medium to the magnetoresistive element, and for returning magnetic flux from the magnetoresistive element to the recording medium. To linearize the reproduction characteristic of the magnetoresistive element, an electrically conducting layer extending parallel to the magnetoresistive element is provided.
Upon the passage of current, a permanent magnetic field is applied at which the magnetoresistive element is magnetically biased in order to set a working point in a linear area of the resistance-magnetic field curve of the magnetoresistive element.
In the known magnetic head, the magnetoresistive element is situated between said flux-guiding layer parts and the magnetically conducting substrate, while a read gap extends between one of the flux-guiding layer parts and the substrate. For technological reasons, the read gap is composed of at least two insulation layers each having such a layer thickness that short-circuit between the magnetoresistive element and the flux-guiding layer parts or the substrate is prevented. Such a configuration has the drawback that it is technologically very difficult to realise very small gap lengths.
The general trend is to try to achieve larger information densities on recording media. One of the measures to that end is to record information at increasingly smaller wavelengths. This implies that very small gap lengths are necessary, not only for writing but also for reading information.
In the known magnetic head, the electrically conducting layer for applying a permanent magnetic field is outside the magnetic yoke. The known magnetic head forms part of a system which also comprises a current source connected to the electrically conducting layer, and a measuring device connected to the magnetoresistive element.